Contact lenses have been used commercially to improve vision since at least the 1950s. The first contact lenses were made of hard materials and as such were somewhat uncomfortable to users. Modern soft contact lenses are made of softer materials, typically hydrogels. Recently soft contact lenses made from silicone hydrogels have been introduced. Silicone hydrogel are water-swollen polymer networks that have high oxygen permeability. These lenses provide a good level of comfort to many lens wearers, but there are some users who experience discomfort and excessive ocular deposits leading to reduced visual acuity when using these lenses, in particular during extended periods of wear such as for several days in a row, for example, up to about 30 days. This discomfort and deposits has been attributed to the hydrophobic character of the surfaces of lenses and the interaction of those surfaces with the protein, lipids and mucin and the hydrophilic surface of the eye.
One way to increase the water content in a silicone hydrogel is to incorporate an internal wetting agent, such as a high molecular weight polymer, which creates more hydrophilic domains that retain more water. Incorporation of internal wetting agents also affects the surface lubricity of the silicone hydrogel depending on morphology and surface roughness. Poly(vinyl pyrrolidone) (PVP) has been used as an internal wetting agent in silicone hydrogels. For example, U.S. Pat. Nos. 6,367,929, 6,822,016, and 7,052,131 disclose PVP present in the reactive monomer mixture in amounts between 1 and 15 weight percent. Poly(N-vinyl-N-methylacetamide) (PVMA) has been used as an internal wetting agent in non-ionic silicone hydrogels. For example, U.S. Pat. Nos. 7,786,185 and 8,022,158 disclose PVMA present in the reactive monomer mixture in amounts between 1 and 15 weight percent. Compositions with higher concentrations of internal wetting agents, however, have not been disclosed. Contact lenses with higher concentrations of internal wetting agents and acceptable physical, mechanical, and biological properties have also not been disclosed.